1. Technical Field
The present disclosure relates to a control method and a system of a brain computer interface (BCI), and more particularly to a control method and a system of a BCI with a stepping delay flickering sequence.
2. Description of Related Art
With the increasing innovation and progress in medical engineering, in recent years, a brain computer interface (BCI) system has been widely applied in a control interface for driving various special devices. For example, action commands from a wheelchair, sickbed or multimedia entertainment device can be converted into corresponding visual stimulation signals through a display device of the BCI system. Then, the BCI system acquires a brain wave signal generated by a user who is gazing at the display device, and determines the action command corresponding to the brain wave signal, so as to perform action control on the related device.
The conventional BCI technology includes a steady-state visual evoked potential (SSVEP) system, a flash visual evoked potential (FVEP) system, a phase tagged flickering sequence VEP system, and a biphasic stimulation VEP system, which are used for generating visual stimulation signals through different visual flickering sequence encoding manners.
However, the SSVEP system can only provide limited visual options, and when multi-frequency stimulation is used to increase the visual options, problems like different brain wave response powers and disordered flashing frames are caused. The FVEP system may generate frames in a chaotic flashing sequence, and may easily be interfered with other physiological signals. The phase tagged flickering sequence VEP system needs to first correct an initial flashing phase due to physiological reaction differences among different users, and may result in an offset of a response phase caused by the visual fatigue of the user after long-time use, so that the flashing phase must be corrected again. The biphasic stimulation VEP system needs to measure reference phases of the visual stimulation signal and the brain wave signal, and thus the redundant data is increased.
Therefore, the conventional technology still has the aforementioned disadvantages and defects to be solved.